One problem facing the present-day rope production is associated with reducing the amount of power consumable by rope making processes through reducing rope pulling forces required for rope making, which in turn requires less metal for fabricating rope-twisting machines, results in smaller machine dimensions, makes operation of the machine easier, and causes less frequent breakdowns.
There is known a rope-twisting machine comprising arranged in succession on the base a drive rotor carrying rope elements to be twisted, a means for squeezing the rope elements in the form of a mandrel rigidly secured on the rotor and having shaping grooves, and a drawing die arranged coaxially with the mandrel (cf., U.S. Pat. No. 2,156,652; Cl. 57-145; published 1939).
The means for squeezing the rope elements defines an annular converging neck portion acting to compress or squeeze the rope elements when they are drawn therethrough.
Also, the machine is provided with an additional squeezing means serving for reducing the twisted rope to the final shape and size.
Squeezing of the rope elements in this machine is effected by continuous and simultaneous contact thereof with the squeezing means. Such a squeezing of the rope elements requires increased pulling forces for drawing them away from the squeezing zone and, as a consequence, increased power expenditures.
In addition, the machine must be provided with a powerful mechanism for drawing the rope and a high-power drive. It must further feature increased strength and rigidity of most of its parts and units interacting with the rope drawing mechanism, whereby it becomes bulky, more complicated in operation and less reliable.
There is also known a rope twisting machine comprising arranged on a base in succession a rotor carrying rope elements, a distribution template, and a mechanism for drawing the rope elements being squeezed (cf., British Pat. No. 1,373,814; Cl. D 07 B, published 1974).
The machine is also provided with a mandrel supporting the rope elements and a drawing die coaxially arranged relative to the mandrel, the mandrel and the draw plate being interposed between the rotor and the drawing mechanism.
The rope elements are squeezed in this machine through drawing them from the squeezing zone at a continuous contact of the finished rope with the working surface of the drawing die, which requires a very considerable pulling force to be applied and consequently results in high energy expenditures.
Another disadvantage resides in that the machine is large in size, requires much metal to be consumed for its fabrication, and is difficult to operate and service.
There is further known a rope-twisting machine taken by the inventors as a prototype and comprising arranged in succession on the base a rotor carrying rope elements, a mandrel having shaping grooves and rigidly connected to the rotor, pressure rollers mounted in a casing with axes of the pressure rollers being arranged in planes passing through the axis of rotation of the rotor.
The machine is also provided with a system of deflectable rollers providing for a continuous contact of the rope elements with the mandrel and pressure rollers in the squeezing zone.
It is to be noted that the number of pressure rollers employed in this machine must not be less than the number of rope elements being squeezed, which increases the overall bulk and size of the machine.
For making ropes by this prior art machine the rope elements (round wires or strands) are drawn between the pressure rollers mounted in the casing and the mandrel having the shaping grooves, where the strands are compressed to a required cross-section, the strands thereupon being fed to twisting dies for laying the rope.
However, the rope twisting machine requires much energy to be consumed for rope making again due to the fact that the rope elements are squeezed by pulling them from the squeezing zone.
The rope twisting machine is also bulky and requires much metal for its manufacture. It is consequently complicated in operation and not sufficiently reliable due to excessive number of parts and units directly involved in squeezing the rope elements.